1. Field of the Invention
This invention is related to lubricants, especially lubricating oils, and fuels, especially hydrocarbon fuels, and, more particularly, to a class of anti-wear, anti-fatigue, and extreme pressure additives that are derived from silanes for such lubricants and fuels.
2. Description of Related Art
In developing lubricating oils, there have been many attempts to provide additives that impart anti-fatigue, anti-wear, and extreme pressure properties thereto. Zinc dialkyldithiophosphates (ZDDP) have been used in formulated oils as anti-wear additives for more than 50 years. However, zinc dialkyldithiophosphates give rise to ash, which contributes to particulate matter in automotive exhaust emissions, and regulatory agencies are seeking to reduce emissions of zinc into the environment. In addition, phosphorus, also a component of ZDDP, is suspected of limiting the service life of the catalytic converters that are used on cars to reduce pollution. It is important to limit the particulate matter and pollution formed during engine use for toxicological and environmental reasons, but it is also important to maintain undiminished the anti-wear properties of the lubricating oil.
In view of the aforementioned shortcomings of the known zinc and phosphorus-containing additives, efforts have been made to provide lubricating oil additives that contain neither zinc nor phosphorus or, at least, contain them in substantially reduced amounts. Illustrative of non-zinc, i.e., ashless, non-phosphorus-containing lubricating oil additives are the reaction products of 2,5-dimercapto-1,3,4-thiadiazoles and unsaturated mono-, di-, and tri-glycerides disclosed in U.S. Pat. No. 5,512,190 and the dialkyl dithiocarbamate-derived organic ethers of U.S. Pat. No. 5,514,189.
U.S. Pat. No. 5,512,190 discloses an additive that provides anti-wear properties to a lubricating oil. The additive is the reaction product of 2,5-dimercapto-1,3,4-thiadiazole and a mixture of unsaturated mono-, di-, and triglycerides. Also disclosed is a lubricating oil additive with anti-wear properties produced by reacting a mixture of unsaturated mono-, di-, and triglycerides with diethanolamine to provide an intermediate reaction product and reacting the intermediate reaction product with 2,5-dimercapto-1,3,4 thiadiazole.
U.S. Pat. No. 5,514,189 discloses that dialkyl dithiocarbamate-derived organic ethers have been found to be effective anti-wear/antioxidant additives for lubricants and fuels.
U.S. Pat. Nos. 5,084,195 and 5,300,243 disclose N-acyl-thiourethane thioureas as anti-wear additives specified for lubricants or hydraulic fluids.
U.S. application Ser. No. 09/872,722, filed Jun. 1, 2001, discloses a composition comprising:                (A) a lubricant, and         (B) at least one 5-alkyl-2-mercapto-1,3,4-oxadiazole compound of the formula: wherein R1 is a hydrocarbyl or functionalized hydrocarbyl of from 1 to 30 carbon atoms.        
Japanese patent publication 8-337788 (Dec. 24, 1996) claims additives consisting of silane compounds., e.g., R1Si(OR)3, (R1)2Si(OR)2, and (R1)3SiOR(R═H, C1-18 alkyl, C2-18 alkenyl, C6-18 aryl; R1=C6-50 alkyl, alkenyl, aryl; the alkyl group in R1 may contain N, O, or S or be substituted with OH, CO2H, alkoxycarbonyl, alkenoxycarbonyl, or aryloxycarbonyl). The lubricating oil compounds contain (1) 0.05-10 wt. % the silane additives or (2) the silane additives, metal detergents, and optionally extreme-pressure agents and ashless dispersants. The additives are said to decrease friction of engine oils and improve piston detergency.
Russian patent 245955 (Jun. 11, 1969) discloses that the antifriction and antiwear properties of mineral oil lubricants are increased by addition of organosilanes. To improve the properties of the lubricants, trialkoxy-organosilanes with various functional groups of the formula (RO)3SiR′X are used, where RO is an alkoxy group, R′ is an alkyl, alkylene, or aryl radical, and X is a functional group, such as NH2, CO2H, COH, OH, or CN.
The disclosures of the foregoing references are incorporated herein by reference in their entirety.